Late TLS certificate verification in WebKitGTK+ prior to 2.6.6 allows remote attackers to view a secure HTTP request, including, for example, secure cookies.
https://webkitgtk.org/security/WSA-2015-0002.html
https://trac.webkit.org/changeset/181074
https://security.gentoo.org/glsa/201706-15
https://bugs.webkit.org/show_bug.cgi?id=142244